#ifndef _LINUX_MM_TYPES_H
#define _LINUX_MM_TYPES_H

#include <linux/auxvec.h>
#include <linux/types.h>
#include <linux/threads.h>
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/rbtree.h>
#include <linux/rwsem.h>
#include <linux/completion.h>
#include <linux/cpumask.h>
#include <linux/uprobes.h>
#include <linux/page-flags-layout.h>
#include <linux/workqueue.h>
#include <asm/page.h>
#include <asm/mmu.h>

#ifndef AT_VECTOR_SIZE_ARCH
#define AT_VECTOR_SIZE_ARCH 0
#endif
#define AT_VECTOR_SIZE (2*(AT_VECTOR_SIZE_ARCH + AT_VECTOR_SIZE_BASE + 1))

struct address_space;
struct mem_cgroup;

#define USE_SPLIT_PTE_PTLOCKS   (NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS)
#define USE_SPLIT_PMD_PTLOCKS   (USE_SPLIT_PTE_PTLOCKS && \
        IS_ENABLED(CONFIG_ARCH_ENABLE_SPLIT_PMD_PTLOCK))
#define ALLOC_SPLIT_PTLOCKS     (SPINLOCK_SIZE > BITS_PER_LONG/8)

/*
 * Each physical page in the system has a struct page associated with
 * it to keep track of whatever it is we are using the page for at the
 * moment. Note that we have no way to track which tasks are using
 * a page, though if it is a pagecache page, rmap structures can tell us
 * who is mapping it.
 *
 * The objects in struct page are organized in double word blocks in
 * order to allows us to use atomic double word operations on portions
 * of struct page. That is currently only used by slub but the arrangement
 * allows the use of atomic double word operations on the flags/mapping
 * and lru list pointers also.
 */
struct page {
    /* First double word block */
    unsigned long flags;        /* Atomic flags, some possibly updated asynchronously
                                              描述page的状态和其他信息  */
    union
    {
        struct address_space *mapping;  /* If low bit clear, points to
                         * inode address_space, or NULL.
                         * If page mapped as anonymous
                         * memory, low bit is set, and
                         * it points to anon_vma object:
                         * see PAGE_MAPPING_ANON below.
                         */
        void *s_mem;            /* slab first object */
        atomic_t compound_mapcount;     /* first tail page */
        /* page_deferred_list().next     -- second tail page */
    };

    /* Second double word */
    struct {
        union {
            pgoff_t index;      /* Our offset within mapping.
            在映射的虚拟空间（vma_area）内的偏移；
            一个文件可能只映射一部分，假设映射了1M的空间，
            index指的是在1M空间内的偏移，而不是在整个文件内的偏移。 */
            void *freelist;     /* sl[aou]b first free object */
            /* page_deferred_list().prev    -- second tail page */
        };

        union {
#if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \
    defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE)
            /* Used for cmpxchg_double in slub */
            unsigned long counters;
#else
            /*
             * Keep _refcount separate from slub cmpxchg_double
             * data.  As the rest of the double word is protected by
             * slab_lock but _refcount is not.
             */
            unsigned counters;
#endif

            struct {

                union {
                    /*
                     * Count of ptes mapped in mms, to show
                     * when page is mapped & limit reverse
                     * map searches.
                     * 页映射计数器
                     */
                    atomic_t _mapcount;

                    struct { /* SLUB */
                        unsigned inuse:16;
                        unsigned objects:15;
                        unsigned frozen:1;
                    };
                    int units;      /* SLOB */
                };
                /*
                 * Usage count, *USE WRAPPER FUNCTION*
                 * when manual accounting. See page_ref.h
                 * 页引用计数器
                 */
                atomic_t _refcount;
            };
            unsigned int active;    /* SLAB */
        };
    };

    /*
     * Third double word block
     *
     * WARNING: bit 0 of the first word encode PageTail(). That means
     * the rest users of the storage space MUST NOT use the bit to
     * avoid collision and false-positive PageTail().
     */
    union {
        struct list_head lru;   /* Pageout list, eg. active_list
                     * protected by zone->lru_lock !
                     * Can be used as a generic list
                     * by the page owner.
                     */
        struct dev_pagemap *pgmap; /* ZONE_DEVICE pages are never on an
                        * lru or handled by a slab
                        * allocator, this points to the
                        * hosting device page map.
                        */
        struct {        /* slub per cpu partial pages */
            struct page *next;      /* Next partial slab */
#ifdef CONFIG_64BIT
            int pages;      /* Nr of partial slabs left */
            int pobjects;   /* Approximate # of objects */
#else
            short int pages;
            short int pobjects;
#endif
        };

        struct rcu_head rcu_head;       /* Used by SLAB
                         * when destroying via RCU
                         */
        /* Tail pages of compound page */
        struct {
            unsigned long compound_head; /* If bit zero is set */

            /* First tail page only */
#ifdef CONFIG_64BIT
            /*
             * On 64 bit system we have enough space in struct page
             * to encode compound_dtor and compound_order with
             * unsigned int. It can help compiler generate better or
             * smaller code on some archtectures.
             */
            unsigned int compound_dtor;
            unsigned int compound_order;
#else
            unsigned short int compound_dtor;
            unsigned short int compound_order;
#endif
        };

#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && USE_SPLIT_PMD_PTLOCKS
        struct {
            unsigned long __pad;    /* do not overlay pmd_huge_pte
                         * with compound_head to avoid
                         * possible bit 0 collision.
                         */
            pgtable_t pmd_huge_pte; /* protected by page->ptl */
        };
#endif
    };

    /* Remainder is not double word aligned */
    union {
        unsigned long private;      /* Mapping-private opaque data:
                         * usually used for buffer_heads
                         * if PagePrivate set; used for
                         * swp_entry_t if PageSwapCache;
                         * indicates order in the buddy
                         * system if PG_buddy is set.
                         * 私有数据指针，由应用场景确定其具体的含义
                         */
#if USE_SPLIT_PTE_PTLOCKS
#if ALLOC_SPLIT_PTLOCKS
        spinlock_t *ptl;
#else
        spinlock_t ptl;
#endif
#endif
        struct kmem_cache *slab_cache;  /* SL[AU]B: Pointer to slab */
    };

#ifdef CONFIG_MEMCG
    struct mem_cgroup *mem_cgroup;
#endif

    /*
     * On machines where all RAM is mapped into kernel address space,
     * we can simply calculate the virtual address. On machines with
     * highmem some memory is mapped into kernel virtual memory
     * dynamically, so we need a place to store that address.
     * Note that this field could be 16 bits on x86 ... ;)
     *
     * Architectures with slow multiplication can define
     * WANT_PAGE_VIRTUAL in asm/page.h
     */
#if defined(WANT_PAGE_VIRTUAL)
    void *virtual;          /* Kernel virtual address (NULL if
                       not kmapped, ie. highmem) */
#endif /* WANT_PAGE_VIRTUAL */

#ifdef CONFIG_KMEMCHECK
    /*
     * kmemcheck wants to track the status of each byte in a page; this
     * is a pointer to such a status block. NULL if not tracked.
     */
    void *shadow;
#endif

#ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS
    int _last_cpupid;
#endif
}
/*
 * The struct page can be forced to be double word aligned so that atomic ops
 * on double words work. The SLUB allocator can make use of such a feature.
 */
#ifdef CONFIG_HAVE_ALIGNED_STRUCT_PAGE
    __aligned(2 * sizeof(unsigned long))
#endif
;





struct page_frag {
    struct page *page;
#if (BITS_PER_LONG > 32) || (PAGE_SIZE >= 65536)
    __u32 offset;
    __u32 size;
#else
    __u16 offset;
    __u16 size;
#endif
};

#define PAGE_FRAG_CACHE_MAX_SIZE    __ALIGN_MASK(32768, ~PAGE_MASK)
#define PAGE_FRAG_CACHE_MAX_ORDER       get_order(PAGE_FRAG_CACHE_MAX_SIZE)

struct page_frag_cache {
    void * va;
#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
    __u16 offset;
    __u16 size;
#else
    __u32 offset;
#endif
    /* we maintain a pagecount bias, so that we dont dirty cache line
     * containing page->_refcount every time we allocate a fragment.
     */
    unsigned int        pagecnt_bias;
    bool pfmemalloc;
};

typedef unsigned long vm_flags_t;

/*
 * A region containing a mapping of a non-memory backed file under NOMMU
 * conditions.  These are held in a global tree and are pinned by the VMAs that
 * map parts of them.
 */
struct vm_region {
    struct rb_node  vm_rb;      /* link in global region tree */
    vm_flags_t      vm_flags;       /* VMA vm_flags */
    unsigned long   vm_start;       /* start address of region */
    unsigned long   vm_end;     /* region initialised to here */
    unsigned long   vm_top;     /* region allocated to here */
    unsigned long   vm_pgoff;       /* the offset in vm_file corresponding to vm_start */
    struct file     *vm_file;       /* the backing file or NULL */

    int         vm_usage;       /* region usage count (access under nommu_region_sem) */
    bool        vm_icache_flushed : 1; /* true if the icache has been flushed for
                        * this region */
};

#ifdef CONFIG_USERFAULTFD
#define NULL_VM_UFFD_CTX ((struct vm_userfaultfd_ctx) { NULL, })
struct vm_userfaultfd_ctx {
    struct userfaultfd_ctx *ctx;
};
#else /* CONFIG_USERFAULTFD */
#define NULL_VM_UFFD_CTX ((struct vm_userfaultfd_ctx) {})
struct vm_userfaultfd_ctx {};
#endif /* CONFIG_USERFAULTFD */

/*
 * This struct defines a memory VMM memory area. There is one of these
 * per VM-area/task.  A VM area is any part of the process virtual memory
 * space that has a special rule for the page-fault handlers (ie a shared
 * library, the executable area etc).
 */
struct vm_area_struct {
    /* The first cache line has the info for VMA tree walking. */

    unsigned long vm_start;     /* Our start address within vm_mm. */
    unsigned long vm_end;       /* The first byte after our end address
                       within vm_mm. */

    /* linked list of VM areas per task, sorted by address */
    struct vm_area_struct *vm_next, *vm_prev;

    struct rb_node vm_rb;

    /*
     * Largest free memory gap in bytes to the left of this VMA.
     * Either between this VMA and vma->vm_prev, or between one of the
     * VMAs below us in the VMA rbtree and its ->vm_prev. This helps
     * get_unmapped_area find a free area of the right size.
     */
    unsigned long rb_subtree_gap;

    /* Second cache line starts here. */

    struct mm_struct *vm_mm;    /* The address space we belong to. */
    pgprot_t vm_page_prot;      /* Access permissions of this VMA. */
    unsigned long vm_flags;     /* Flags, see mm.h. */

    /*
     * For areas with an address space and backing store,
     * linkage into the address_space->i_mmap interval tree.
     */
    struct {
        struct rb_node rb;
        unsigned long rb_subtree_last;
    } shared;

    /*
     * A file's MAP_PRIVATE vma can be in both i_mmap tree and anon_vma
     * list, after a COW of one of the file pages.  A MAP_SHARED vma
     * can only be in the i_mmap tree.  An anonymous MAP_PRIVATE, stack
     * or brk vma (with NULL file) can only be in an anon_vma list.
     */
    struct list_head anon_vma_chain; /* Serialized by mmap_sem &
                      * page_table_lock */
    struct anon_vma *anon_vma;      /* Serialized by page_table_lock */

    /* Function pointers to deal with this struct. */
    const struct vm_operations_struct *vm_ops;

    /* Information about our backing store: */
    unsigned long vm_pgoff;     /* Offset (within vm_file) in PAGE_SIZE
                       units */
    struct file * vm_file;      /* File we map to (can be NULL). */
    void * vm_private_data;     /* was vm_pte (shared mem) */

#ifndef CONFIG_MMU
    struct vm_region *vm_region;    /* NOMMU mapping region */
#endif
#ifdef CONFIG_NUMA
    struct mempolicy *vm_policy;    /* NUMA policy for the VMA */
#endif
    struct vm_userfaultfd_ctx vm_userfaultfd_ctx;
};

struct core_thread {
    struct task_struct *task;
    struct core_thread *next;
};

struct core_state {
    atomic_t nr_threads;
    struct core_thread dumper;
    struct completion startup;
};

enum {
    MM_FILEPAGES,   /* Resident file mapping pages */
    MM_ANONPAGES,   /* Resident anonymous pages */
    MM_SWAPENTS,    /* Anonymous swap entries */
    MM_SHMEMPAGES,  /* Resident shared memory pages */
    NR_MM_COUNTERS
};

#if USE_SPLIT_PTE_PTLOCKS && defined(CONFIG_MMU)
#define SPLIT_RSS_COUNTING
/* per-thread cached information, */
struct task_rss_stat {
    int events;     /* for synchronization threshold */
    int count[NR_MM_COUNTERS];
};
#endif /* USE_SPLIT_PTE_PTLOCKS */

struct mm_rss_stat {
    atomic_long_t count[NR_MM_COUNTERS];
};

struct kioctx_table;
struct mm_struct {
    struct vm_area_struct *mmap;        /* list of VMAs */
    struct rb_root mm_rb;
    u32 vmacache_seqnum;           /* per-thread vmacache */
#ifdef CONFIG_MMU
    unsigned long (*get_unmapped_area) (struct file *filp,
                unsigned long addr, unsigned long len,
                unsigned long pgoff, unsigned long flags);
#endif
    unsigned long mmap_base;        /* base of mmap area */
    unsigned long mmap_legacy_base;     /* base of mmap area in bottom-up allocations */
    unsigned long task_size;        /* size of task vm space */
    unsigned long highest_vm_end;       /* highest vma end address */
    pgd_t * pgd;
    atomic_t mm_users;              /* How many users with user space? */
    atomic_t mm_count;              /* How many references to "struct mm_struct" (users count as 1) */
    atomic_long_t nr_ptes;          /* PTE page table pages */
#if CONFIG_PGTABLE_LEVELS > 2
    atomic_long_t nr_pmds;          /* PMD page table pages */
#endif
    int map_count;              /* number of VMAs */

    spinlock_t page_table_lock;         /* Protects page tables and some counters */
    struct rw_semaphore mmap_sem;

    struct list_head mmlist;        /* List of maybe swapped mm's.  These are globally strung
                         * together off init_mm.mmlist, and are protected
                         * by mmlist_lock
                         */


    unsigned long hiwater_rss;      /* High-watermark of RSS usage */
    unsigned long hiwater_vm;       /* High-water virtual memory usage */

    unsigned long total_vm;     /* Total pages mapped */
    unsigned long locked_vm;    /* Pages that have PG_mlocked set */
    unsigned long pinned_vm;    /* Refcount permanently increased */
    unsigned long data_vm;      /* VM_WRITE & ~VM_SHARED & ~VM_STACK */
    unsigned long exec_vm;      /* VM_EXEC & ~VM_WRITE & ~VM_STACK */
    unsigned long stack_vm;     /* VM_STACK */
    unsigned long def_flags;
    unsigned long start_code, end_code, start_data, end_data;
    unsigned long start_brk, brk, start_stack;
    unsigned long arg_start, arg_end, env_start, env_end;

    unsigned long saved_auxv[AT_VECTOR_SIZE]; /* for /proc/PID/auxv */

    /*
     * Special counters, in some configurations protected by the
     * page_table_lock, in other configurations by being atomic.
     */
    struct mm_rss_stat rss_stat;

    struct linux_binfmt *binfmt;

    cpumask_var_t cpu_vm_mask_var;

    /* Architecture-specific MM context */
    mm_context_t context;

    unsigned long flags; /* Must use atomic bitops to access the bits */

    struct core_state *core_state; /* coredumping support */
#ifdef CONFIG_AIO
    spinlock_t              ioctx_lock;
    struct kioctx_table __rcu       *ioctx_table;
#endif
#ifdef CONFIG_MEMCG
    /*
     * "owner" points to a task that is regarded as the canonical
     * user/owner of this mm. All of the following must be true in
     * order for it to be changed:
     *
     * current == mm->owner
     * current->mm != mm
     * new_owner->mm == mm
     * new_owner->alloc_lock is held
     */
    struct task_struct __rcu *owner;
#endif

    /* store ref to file /proc/<pid>/exe symlink points to */
    struct file __rcu *exe_file;
#ifdef CONFIG_MMU_NOTIFIER
    struct mmu_notifier_mm *mmu_notifier_mm;
#endif
#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
    pgtable_t pmd_huge_pte; /* protected by page_table_lock */
#endif
#ifdef CONFIG_CPUMASK_OFFSTACK
    struct cpumask cpumask_allocation;
#endif
#ifdef CONFIG_NUMA_BALANCING
    /*
     * numa_next_scan is the next time that the PTEs will be marked
     * pte_numa. NUMA hinting faults will gather statistics and migrate
     * pages to new nodes if necessary.
     */
    unsigned long numa_next_scan;

    /* Restart point for scanning and setting pte_numa */
    unsigned long numa_scan_offset;

    /* numa_scan_seq prevents two threads setting pte_numa */
    int numa_scan_seq;
#endif
#if defined(CONFIG_NUMA_BALANCING) || defined(CONFIG_COMPACTION)
    /*
     * An operation with batched TLB flushing is going on. Anything that
     * can move process memory needs to flush the TLB when moving a
     * PROT_NONE or PROT_NUMA mapped page.
     */
    bool tlb_flush_pending;
#endif
    struct uprobes_state uprobes_state;
#ifdef CONFIG_X86_INTEL_MPX
    /* address of the bounds directory */
    void __user *bd_addr;
#endif
#ifdef CONFIG_HUGETLB_PAGE
    atomic_long_t hugetlb_usage;
#endif
#ifdef CONFIG_MMU
    struct work_struct async_put_work;
#endif
};

static inline void mm_init_cpumask(struct mm_struct *mm)
{
#ifdef CONFIG_CPUMASK_OFFSTACK
    mm->cpu_vm_mask_var = &mm->cpumask_allocation;
#endif
    cpumask_clear(mm->cpu_vm_mask_var);
}

/* Future-safe accessor for struct mm_struct's cpu_vm_mask. */
static inline cpumask_t *mm_cpumask(struct mm_struct *mm)
{
    return mm->cpu_vm_mask_var;
}

#if defined(CONFIG_NUMA_BALANCING) || defined(CONFIG_COMPACTION)
/*
 * Memory barriers to keep this state in sync are graciously provided by
 * the page table locks, outside of which no page table modifications happen.
 * The barriers below prevent the compiler from re-ordering the instructions
 * around the memory barriers that are already present in the code.
 */
static inline bool mm_tlb_flush_pending(struct mm_struct *mm)
{
    barrier();
    return mm->tlb_flush_pending;
}
static inline void set_tlb_flush_pending(struct mm_struct *mm)
{
    mm->tlb_flush_pending = true;

    /*
     * Guarantee that the tlb_flush_pending store does not leak into the
     * critical section updating the page tables
     */
    smp_mb__before_spinlock();
}
/* Clearing is done after a TLB flush, which also provides a barrier. */
static inline void clear_tlb_flush_pending(struct mm_struct *mm)
{
    barrier();
    mm->tlb_flush_pending = false;
}
#else
static inline bool mm_tlb_flush_pending(struct mm_struct *mm)
{
    return false;
}
static inline void set_tlb_flush_pending(struct mm_struct *mm)
{
}
static inline void clear_tlb_flush_pending(struct mm_struct *mm)
{
}
#endif

struct vm_fault;

struct vm_special_mapping {
    const char *name;       /* The name, e.g. "[vdso]". */

    /*
     * If .fault is not provided, this points to a
     * NULL-terminated array of pages that back the special mapping.
     *
     * This must not be NULL unless .fault is provided.
     */
    struct page **pages;

    /*
     * If non-NULL, then this is called to resolve page faults
     * on the special mapping.  If used, .pages is not checked.
     */
    int (*fault)(const struct vm_special_mapping *sm,
             struct vm_area_struct *vma,
             struct vm_fault *vmf);
};

enum tlb_flush_reason {
    TLB_FLUSH_ON_TASK_SWITCH,
    TLB_REMOTE_SHOOTDOWN,
    TLB_LOCAL_SHOOTDOWN,
    TLB_LOCAL_MM_SHOOTDOWN,
    TLB_REMOTE_SEND_IPI,
    NR_TLB_FLUSH_REASONS,
};

 /*
  * A swap entry has to fit into a "unsigned long", as the entry is hidden
  * in the "index" field of the swapper address space.
  */
typedef struct {
    unsigned long val;
} swp_entry_t;

#endif /* _LINUX_MM_TYPES_H */
